5 years undergraduate Physics+Astronomy program at Univ. of Warsaw, Poland

1. ASTA01 – Intro to Astr. & Astrophys. I: the Sun and Planets Introducing the lecturer: Pawel Artymowicz (UofT) • 5 years undergraduate Physics+Astronomy program at Univ. of Warsaw, Poland • 4 years graduate study at the Space Telescope Science Institute, Baltimore, MD.

2. ASTA01 – Intro to Ast. & Astroph. I: the sun and planets Introducing the lecturer: Pawel Artymowicz (UofT) • 3 years postdoctoral NASA Hubble Fellow at Univ. of California, Santa Cruz (UCSC), USA • 11 years senior researcher, asst. and assoc. prof. in Stockholm University, Sweden • 8 years full tenured prof. UofT, Canada.

3. ASTA01 – Intro to Ast. & Astroph. I: the sun and planets Areas of expertise: • Planetary system origins Dusty disks like Beta Pictoris, dust avalanches, dust disk instabilities Migration of protoplanets in disks Numerical hydrodynamics, GPU computing • Binary stars • Galactic dynamics, black holes and active galactic nuclei • Aerodynamics and aviation

4. ASTA01 – Intro to Ast. & Astroph. I: the sun and planets Where to look for course information: syllabus, lecturer’s contact information etc. • Blackboard page of ASTA01 • Additional, linked course URL on planets.utsc.utoronto.ca server of P.A. • Your TA during and after tutorial

5. ASTA01 – Intro to Ast. & Astroph. I: the sun and planets • You are about to go on a voyage to the limits of the known universe. Chapter 1The Scale of the Cosmos: Space and Time

6. You will travel outward, away from your home on Earth, past the moon and the sun and the other planets of our solar system, past the stars you see in the night sky, and beyond billions more stars that can be seen only with the aid of telescopes.

7. You will visit the most distant galaxies – great globes and whirlpools of stars. Then, you will continue on, carried only by experience and imagination, seeking to understand the structure of the universe. (that’s coming in ASTA02, next term!)

8. Astronomy is more than the study of planets, stars, and galaxies. It is the study of the whole universe in which you live.

9. Humanity is confined to a small planet circling an average star. The study of astronomy can take you beyond these boundaries and help you not only see where you are in the universe, but understand what you are. You will see how science works and how it solves the oldest questions asked by humankind, such as the existence of other planets like our own, and other solar systems.

10. Your imagination is the key to discovery. It will be your scientific space-and-time machine, transporting you across the universe and into the past and future.

11. Although you will see evidence of a beginning to the universe, you will not find an edge or an end in space. No matter how far you voyage, you will not run into a wall. The universe may be infinite. That is, it may extend in all directions without limit. About 90 years ago astronomers found that the universe expands. About 13 years ago they found that it is expanding at an accelerating pace. Nobody yet knows exactly why.

12. Astronomy will introduce you to sizes, distances, and times far beyond your usual experience on Earth. Your task in this chapter is to grasp the meaning, the scale, of these unfamiliar sizes, distances, and times.

13. In this chapter, you will compare objects of different sizes in order to comprehend the scale of the universe.

14. From Solar System to Galaxy to Universe We can start very close to an interesting object in the garden of the CERN visitor centre. [Originally: Conseil Européen pour la Recherche Nucléaire] CERN is the home of the Large Hadron Collider, the largest particle accelerator in operation today, which was designed to simulate the beginning of the universe.

15. From Solar System to Galaxy to Universe Bubble chambers were an important tool for the study of particle physics from the 1950s to the 1980s, though they are now most likely to be seen as museum exhibits.

16. From Solar System to Galaxy to Universe Not more than 100 metres under the ground from the garden, massive detectors are looking for the first signs of the big bang, microscopic black holes, dark matter. The results might shed light on many topics in this book, and perhaps even change a few chapters. We indeed live in exciting times! Physicists study collision of objects on the scale < 0.000000000000001 m = 1 fm (femtometer or fermi)

17. From Solar System to Galaxy to Universe • Our journey will start 10 metres from the garden. • Each view in the following sequence will be made from a distance away that is 10 times larger, until we come to such large distances we will jump with higher increments.

18. From Solar System to Galaxy to Universe Every time you move 10 times away, your field of view encompasses an area 10 x 10 larger than the previous square. Distances are first expressed as 1, 10, or 100 metres, until we come to such large distances that a metre becomes too small as a unit.

19. From Solar System to Galaxy to Universe We start using either prefixes (e.g., “kilo,” which means “one thousand”) or scientific notation (i.e., using powers of 10). For example: 101 = 10 102 = 10 * 10 = 100 103 = 10 * 10 * 10 = 1000 (kilo) …. 106 = 1,000,000 (mega) 109 = 1,000,000,000 (giga) 1012= 1,000,000,000,000 (tera) (…) peta, exa, ….

20. From Solar System to Galaxy to Universe • At a distance of 10 km, the image covers about the same area as CERN’s Large Hadron Collider (LHC).

21. From Solar System to Galaxy to Universe • Ten times farther away, we can see Lake Geneva and part of the Alps mountain chain; 10 times farther again, we see Switzerland and its neighbors, with a more extensive view of the Alps. • [can you spot errors in • illustrations in our textbook?]

22. From Solar System to Galaxy to Universe The Alps started forming 100 million years ago when the African tectonic plate started to move toward the European plate, and the bottom of the sea rose to form new mountains. The Alps still gain about one millimetre in height every year, but since erosion is faster, they will eventually round off and disappear.

23. From Solar System to Galaxy to Universe Mountains and valleys are only temporary features on Earth that are slowly but constantly changing. As you explore the universe, you will come to see that it, too, is always evolving.

24. From Solar System to Galaxy to Universe In the next step of the journey, you will see the entire planet Earth, which is about 13 000 kilometres in diameter. This picture shows most of the daylight side of the planet. However, the blurriness at theextreme right is the sunset line.

25. From Solar System to Galaxy to Universe The rotation of Earth on its axis each 24 hours carries you eastward, and as you cross the sunset line into darkness you say that the Sun has set. At the scale of this figure, the atmosphere on which your life depends is thinner than a strand of thread.

26. From Solar System to Galaxy to Universe Enlarge your field of view again by a factor of 100, and you see a region 1 000 000 kilometres wide. Earth is the small blue dot in the centre, and the Moon – with a diameter only about 1/4 that of Earth – is an even smaller dot along its orbit.

27. From Solar System to Galaxy to Universe If you’ve had a high-mileage car, it may have travelled the equivalent of a trip to the Moon. The average distance of the Moon from Earth of 380 000 kilometres. These numbers are so large that it is inconvenient to write them out.

28. From Solar System to Galaxy to Universe Astronomy is the science of big numbers, and you will use numbers much larger than these to describe the universe. Here, we will jump to another measuring unit.

29. From Solar System to Galaxy to Universe We enlarge a picture not 10 times or 100 times, but 150 times in order to fit a specific distance into the picture, the average distance from Earth to the Sun. This distance is called the Astronomical Unit (AU). It is 1.5 * 108 km = 150 mln km = = 1.5 * 1011 m. Introducing new units is another way astronomers deal with large numbers.

30. From Solar System to Galaxy to Universe Using the Astronomical Unit, you can then say, for example, that the average distance from Venus to the Sun is about 0.7 AU. 0.7 AU

31. From Solar System to Galaxy to Universe The solar system consists of the Sun, its family of planets, and some smaller bodies, such as moons, asteroids, and comets. Like Earth, Venus and Mercury are planets – small, nonluminous bodies that shine by reflecting sunlight.

32. From Solar System to Galaxy to Universe Venus is about the size of Earth, and Mercury is a bit larger than Earth’s moon. In this figure they are both too small to be seen as anything but tiny dots.

33. From Solar System to Galaxy to Universe The Sun is a star, a self-luminous ball of hot gas that generates its own energy. The Sun is about 110 times larger in diameter than Earth, ~1.4 million km, but it, too, is nothing more than a dot in the previous view. Earth orbits the Sun once a year.

34. From Solar System to Galaxy to Universe Now we are jumping in increments of 100 times farther away than the previous view. Here you see the entire solar system, all the major planets, and their slightly elliptical orbits. The details of the Earth & Venus orbit are lost in the red square at the centre. Scale: 100 AU

35. From Solar System to Galaxy to Universe Light from the Sun reaches Earth in only 8 minutes, but it takes over 4 hours to reach Neptune. Pluto orbits mostly outside Neptune’s orbit, but it is no longer considered a major planet. Scale: 100 AU

36. From Solar System to Galaxy to Universe When you again move away 100 times farther, the solar system becomes invisibly small. The Sun is only a point of light, and all the planets and their slightly elliptical orbits are now crowded into the small red square at the centre. Scale: 10000 AU

37. From Solar System to Galaxy to Universe The planets and the comets are too small and reflect too little light to be visible so near the brilliance of the Sun. Nor are any stars visible except for the Sun. Scale: 10000 AU

38. From Solar System to Galaxy to Universe The Sun is a fairly typical star, a bit larger than average, and it is located in a fairly normal neighbourhood in the universe. Although there are many billions of stars like the Sun, none is close enough to be visible in the figure.

39. From Solar System to Galaxy to Universe The stars are separated by average distances about 30 times larger than this view Scale: 10000 AU

40. From Solar System to Galaxy to Universe It is difficult to grasp the great isolation of the stars. If the Sun were represented by a golf ball in Toronto, the nearest star would be another golf ball in Quebec City or Chicago.

41. From Solar System to Galaxy to Universe In this figure, your view has expanded to a diameter a bit over one million AU. The Sun is at the centre, and you see a few of the nearest stars. Symbol ~ means ‘of order’ Or ‘order of magnitude’ Or ‘roughly equal to’ Scale: ~106 AU

42. From Solar System to Galaxy to Universe These stars are so distant that it is not reasonable to give their distances in AU. Astronomers have defined a new, larger unit of distance – the light-year. One light-year (ly) is the distance that light travels in 1 year, ~1013 km = 63 000 AU. Scale: ~17 ly (lyr)

43. From Solar System to Galaxy to Universe One of the nearest stars to the Sun, Proxima Centauri, is 4.2 ly from Earth. In other words, light from Proxima Centauri takes 4.2 years to reach us. 4.3 ly from us is a companion Alpha Cen B. An Earth-mass planet was discovered 1yr ago around it!

44. From Solar System to Galaxy to Universe Although these stars are roughly the same size as the Sun, they are so far away that you cannot see them as anything but points of light. Even with the largest single telescopes on Earth, you still see only points of light when you look at stars, and any planets that might circle those stars are usually much too small and faint to be visible [but there are exceptions…]

45. From Solar System to Galaxy to Universe Here the sizes of the dots represent not the sizes of the stars but their brightness. This is the custom in astronomical diagrams, and it is also how starlight is recorded. Bright stars make larger spots than faint stars in a photograph or electronic picture. The size of a star image in a photograph tells you not how big the star really is but only how bright it looks.

46. From Solar System to Galaxy to Universe • Here, you expand your field of view by another factor of 100, and the Sun and its neighbouring stars vanish into the background of thousands of stars. • This figure has scale of 1700 ly in diameter.

47. From Solar System to Galaxy to Universe • Of course, no one has ever journeyed thousands of light-years from Earth to look back and photograph the Sun’s neighbourhood, so this is a representative picture from Earth of a part of the sky that can be used as a reasonable analogy.

48. From Solar System to Galaxy to Universe • The Sun is faint enough that it would not be easily located in a picture at this scale.

49. From Solar System to Galaxy to Universe Some things that are invisible in this figure are actually critically important. You do not see the thin gas that fills the spaces between the stars. Although these clouds of gas are thinner than the best vacuum produced in laboratories on Earth, it is these clouds that give birth to new stars.

50. From Solar System to Galaxy to Universe • The Sun formed from such a cloud about 4.56 billion years ago (4.56 Gy ago).